Solve for $x$ and $y$ using substitution. ${-5x-4y = 1}$ ${x = -4y+3}$
Answer: Since $x$ has already been solved for, substitute $-4y+3$ for $x$ in the first equation. ${-5}{(-4y+3)}{- 4y = 1}$ Simplify and solve for $y$ $20y-15 - 4y = 1$ $16y-15 = 1$ $16y-15{+15} = 1{+15}$ $16y = 16$ $\dfrac{16y}{{16}} = \dfrac{16}{{16}}$ ${y = 1}$ Now that you know ${y = 1}$ , plug it back into $\thinspace {x = -4y+3}\thinspace$ to find $x$ ${x = -4}{(1)}{ + 3}$ $x = -4 + 3$ ${x = -1}$ You can also plug ${y = 1}$ into $\thinspace {-5x-4y = 1}\thinspace$ and get the same answer for $x$ : ${-5x - 4}{(1)}{= 1}$ ${x = -1}$